<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Java后端WebSocket的Tomcat实现</title>
</head>
<body>
<input id="id" type="text"/>
<button onclick="connect()">连接</button>
<p></p>
<hr/>
<span>text:</span>
<input id="text" type="text"/>
<span>id:</span>
<input value="" id="toid" type="text"/>

<button onclick="send()">发送消息</button>
<hr/>
<button onclick="closeWebSocket()">关闭WebSocket连接</button>
<hr/>
<div id="message"></div>
</body>

<script type="text/javascript">
    var websocket = null;
    var id = document.getElementById("id");
    var toid = document.getElementById("toid");

    function connect(){
        //判断当前浏览器是否支持WebSocket
        if ('WebSocket' in window) {
            var socketUrl = window.location.protocol+"//zjgk.top:"+window.location.port+"/websocket/"+ id.value;
            socketUrl = socketUrl.replace("https", "wss").replace("http", "ws");
            console.log(socketUrl);

            websocket = new WebSocket(socketUrl);
        }
        else {
            alert('当前浏览器 Not support websocket')
        }
        //连接发生错误的回调方法
        websocket.onerror = function () {
            setMessageInnerHTML("WebSocket连接发生错误");
        };

        //连接成功建立的回调方法
        websocket.onopen = function () {
            setMessageInnerHTML("WebSocket连接成功");
        }

        //接收到消息的回调方法
        websocket.onmessage = function (event) {
                        setMessageInnerHTML(event.data);
        }

        //连接关闭的回调方法
        websocket.onclose = function () {
            setMessageInnerHTML("WebSocket连接关闭");
        }

        //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = function () {
            closeWebSocket();
        }

    }



    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    //关闭WebSocket连接
    function closeWebSocket() {
        websocket.close();
    }

    //发送消息
    function send() {

        var message = document.getElementById('text').value;
        info = {"to":toid.value,"text":message}
        var s = JSON.stringify(info);

        websocket.send(s);
    }
</script>
</html>